CHLORIC ACID. 3G9 



to convert the hypochlorite into a mixture of chlorate and 

 chloride ; but by adding the acid in a gradual manner to the 

 alkaline solution, hypochlorites of potash, soda, lime, barytes 

 and strontian may be formed, and may even be obtained in a solid 

 state by evaporation in vacuo, if a considerable excess of alkali be 

 present, which appears to give a certain degree of stability to 

 these salts. They bleach powerfully, and their odour and colour 

 are identically the same as the corresponding decolorizing com- 

 pounds of chlorine, from which it is impossible to distinguish 

 them by their physical properties. They are salts of a very 

 changeable constitution; a slight increase of temperature, the 

 influence of solar light, even of diffused light, converts them into 

 chlorides and chlorates. It is the opinion of M. Balard that bleach- 

 ing powder, formed by exposing hydrate of lime to chlorine, is a 

 mixture of hypochlorite of lime and chloride of calcium ; but to 

 this subject I shall again return under the salts of lime. 



The euchlorine gas of Davy, to which he assigned the compo- 

 sition of hypochlorous acid, has been found to be a mixture of 

 chlorine and chlorous acid gases. That mixture is obtained by the 

 action of hydrochloric acid of sp. gr. 1.1 upon chlorate of potash, 

 aided by a gentle heat. It has a very yellow colour (euchlorine), 

 and explodes feebly when a hot wire is introduced into it, becom- 

 ing nearly colourless, when the chlorous acid is decomposed. 



Chloric acid, Cl O 5 . When a stream of chlorine gas is trans- 

 mitted through a strong solution of caustic potash, the gas is 

 absorbed, and a solution is formed which bleaches at first, but 

 looses that property without any escape of gas, and becomes a 

 mixture of chloride of potassium and chlorate of potash, the 

 latter of which, being the least soluble, separates in shining 

 tabular crystals. Five equivalents of potash (the oxide of po- 

 tassium) are decomposed by 6 of chlorine, 5 of which unite with 

 the potassium and form 5 equivalents of chloride of potassium, 

 while the 5 of oxygen form chloric acid with the remaining 

 equivalent of chlorine, as stated in the following diagram : 



ACTION OP CHLORINE UPON POTASH. 



Before decomposition. After decomposition. 



5 Chlorine . 5 Chlorine .^5 Chloride of potassium, 

 f 5 Potassium--^"" 



5 Potash . ( 5 oxygen.. 



Chlorine . . Chlorine ^-Chloric acid 1 Chlorate of 



Potash . . . Potash Potash / potash. 



B B 



